Effects of polyacrylamide and nonylphenol polyoxyethylene ether used in oil fields on soil enzyme activities and microbial growth characteristics

The widespread application of chemical displacement technology in oil fields has led to the enrichment of oilfield chemicals in soil. The effects of residual oilfield chemicals on soil enzyme activity and microbial growth characteristics are still unclear. In this work, polyacrylamide (PAM) and nonylphenol polyoxyethylene ether (NP-40), which are commonly used in oil production, are taken as the research objects, and the effects of their concentration changes on soil enzyme activity and microbial growth characteristics are investigated. As the concentration of PAM and NP-40 increases, some indicators show a pattern of "low concentration promotion, high concentration inhibition," including catalase activity, dehydrogenase activity, nitrification potential, microbial biomass, and other indicators. However, there are also some test results that show different patterns. As the dosage of PAM and NP-40 increases, urease activity gradually decreases, and the content of microbial proteins and polysaccharides shows a trend of first decreasing, then increasing, and then decreasing. The addition of oilfield chemicals reduces the species diversity and abundance of soil bacterial communities. In addition, PAM and NP-40 may disrupt the growth cycle of bacteria and disrupt their normal morphology, thereby reducing their normal physiological functions and even leading to their death.